Earlier this week, I shared with you my tutorial on how to make caramelized onions the traditional way. On the stove. Low and slow. With 40 minutes of basically constant stirring. It’s the way that people have been making caramelized onions forever and ever, and with good reason. The technique will yield you some crazy delicious onions.
But.
Awhile back, I heard a little “rumor” (ok, I saw something on Pinterest) about the possibility of making caramelized onions in the slow cooker, and I immediately had to investigate. The idea seemed too simple. Just throw onions and butter in the slow cooker and let them cook for hours and hours and hours, without having to babysit the crock pot and stir them every few minutes, and go through the process of deglazing the pan?!? Nope, I figured there was no way it could work, or that those onions would have the same delicious flavor of their stovetop counterparts. No way.
But I’m here to tell you today — yes way.
My brilliant slow cooker once again proved to me that it can do just about anything. And I have been making batch after batch of heavenly slow cooker caramelized onions ever since. And if you love caramelized onions, you absolutely need to try this too.
First off, I will still always be a fan of the traditional stovetop method for making caramelized onions. And if you’ve never tried making them yourself, I highly recommend adding this method to your skill set.
However.
It’s no secret that I’m all for any shortcuts that fall in the “quick and easy” category with cooking. And once I learned how unbelievably low-maintenance and easy the slow cooker method was, and how ridiculously delicious the onions would turn out, you’d better believe I became an instant fan.
And I’m here to tell you — it literally couldn’t be easier.
Just slice up a bunch of onions. (You can use white, yellow, or red onions, or a combination of any of those.) Toss them with some melted butter. Then let them cook on low for about 12 hours total until they reach that perfectly caramelized, deep golden brown, sweet and savory perfection.
Yep. It really is that easy.
A few tips though:
Lid Ajar: The onions will definitely release lots of natural juices while cooking, which can make the onions slightly soupy near the end. So if you would like that liquid to evaporate, thus making your onions a little thicker and “jammier”, just set the slow cooker lid slightly ajar (1-inch of so) for the final few hours of cooking.
Balsamic and Brown Sugar: I happen to fall in the camp of believing that caramelized onions are plenty flavorful on their own. But if you taste them in the final few hours and decide that they need some extra flavor, just stir in some balsamic vinegar and brown sugar to taste. They will provide the extra savory and sweetness that many people love.
Know Your Slow Cooker: These onions should be able to cook unattended for 10+ hours without any babysitting or stirring. (Although I do recommend stirring them once or twice if you can.) But that said, every slow cooker is different. And the low heat setting on yours could be hotter than most. So, as is good common sense with any slow cooking, I just recommend keeping watch especially during your first batch to be sure that the onions do not burn on the bottom.
So are you ready to give these a try??
I seriously hope you do…and then report back with how they turn out. Enjoy!!
Slow Cooker Caramelized Onions
- Prep Time: 10 minutes
- Cook Time: 720 minutes
- Total Time: 730 minutes
- Yield: 0 About 3 cups 1x
Description
These slow cooker caramelized onions are unbelievably easy to make, and only require 2 main ingredients!
Ingredients
- 3-4 pounds white, yellow or red onions, peeled and thinly sliced
- 3 tablespoons butter (or olive oil), melted
- salt and pepper
- optional: 1 tablespoon of brown sugar and 2 teaspoons of balsamic vinegar
Instructions
- Add onions to the bowl of your slow cooker. Drizzle the melted butter evenly over the top of them, then toss with a spoon (or with your hands) until the onions are evenly coated in the butter.
- Cook on low for 8-10 hours, stirring once or twice if desired, until the onions are a rich golden brown and caramelized. Season with salt and pepper (and brown sugar and/or balsamic, if desired), and stir to combine.
- If your onions are really juicy at this point, set the lid an inch or so ajar. If they are not, leave the lid on regularly to seal in the moisture. Then continue cooking the onions for an additional 3-4 hours until most of the extra liquid has evaporated and the onions are a deep golden brown, and thick and “jammy”.
- Serve the onions immediately, or cover and refrigerate for up to 3 days. Or freeze for up to 3 months.
Notes
Lid Ajar: The onions will definitely release lots of natural juices while cooking, which can make the onions slightly soupy near the end. So if you would like that liquid to evaporate, thus making your onions a little thicker and “jammier”, just set the slow cooker lid slightly ajar (1-inch of so) for the final few hours of cooking.
Balsamic and Brown Sugar: I happen to fall in the camp of believing that caramelized onions are plenty flavorful on their own. But if you taste them in the final few hours and decide that they need some extra flavor, just stir in some balsamic vinegar and brown sugar to taste. They will provide the extra savory and sweetness that many people love.
Know Your Slow Cooker: These onions should be able to cook unattended for 10+ hours without any babysitting or stirring. (Although I do recommend stirring them once or twice if you can.) But that said, every slow cooker is different. And the low heat setting on yours could be hotter than most. So, as is good common sense with any slow cooking, I just recommend keeping watch especially during your first batch to be sure that the onions do not burn on the bottom.
Can you can them after this process and if so, how long would they need to process?
Thank you!
This is almost the recipe I’ve used for the last 15 years and a) yes, it *IS* as easy as we’re saying and b) yes, it tastes as GREAT as we say it does! :-)
By “almost,” I mean…
• I absolutely *stuff* my slow cooker with onions. In fact, for the first hour or so, the lid doesn’t fit on the slow cooker. The reduction in onions as they cook is absolutely ridiculous, so I make sure there’re a ton of onions to start.
• I only use butter, never any oils. I just think it gives the onions a significantly better flavor.
• A bit of garlic paste (1-2 tsp.) never hurt anyone/thing.
• I start the onions off with two hours on HIGH, then 4-6 hours on LOW. Turns out a great product, every time. Sometimes it takes the whole two hours to condense enough raw onions that the lid will fit on the slow cooker.
• Don’t cook off the excess liquid at the end of the cooking time! When you note that you are boiling your onions rather than cooking them, just pour off the excess liquid into an air-tight container, let cool and then refrigerate or freeze. Use it 1:1 with beef broth for a robust French Onion soup, in casseroles, other soups, pot pies, stews, etc. It’s a fantastic and virtually free incredible ingredient.
Oh, and no skinny little fine cuts of onion for me. At best, you can call my Vidalias “rough cuts.” I found that no matter what I do, what scheme of cooking plan I use, fine-cut onions burn on me every time. So rough-cut onions it is… no burning, just beautiful browning with a sweet, caramelized product at the end.
So easy and they taste AMAZING!!!!
I’ve coked onions this way for many years. For those of you wanting to cut calories and fat, slice a lot of onions, enough to pretty much fill the crock, and put them in the slow cooker with no butter, no broth, no salt, no pepper, nothing. Just the onions. Cook them on LOW for 24 hours. Don’t stir them, don’t peek. Just set a timer and at 24 hours, take off the lid, stir them, and proceed.
I freeze them in half cup servings and use them for all sorts of things, including delicious single serving French onion soup.
Just add broth after the onions have been simmering for 8 hours and you make the easiest onion soup ever.
This concept is an awesome new discovery for me! With ADD, any distraction can pull me away from the stove and I end up burning things, so, this might be a game-changer for me. :)
I made these in my crockpot and they were perfect. Tank yo so mu cof the easy and delicious recipe!!
What do I do with this many onions?
I found a little trick to prevent stuff from burning in a slow cooker: one, use a slow cooker liner and two put a cup or two of water between the slow cooker and the liner. This prevents hot spots because the water acts as a buffer and spreads the heat out. Plus it makes cleanup simple.
Loved the recipe, helps when making large batches of Onion dip.
I must have done something wrong. We used the mandolin to slice the onions then tossed with butter, salt and pepper. We use a 5lb bag of white sweet onions and probably a little more than 3 tbs of butter for the extra lb of onions. They started to burn on the sides so stirring to push them down was inevitable. At the end of probably 15 hours of checking the still soupy onions and leaving the lid ajar, they ended up looking burnt on the top and soupy on the bottom. Did I stir it too much? How did it still end up soupy?
Probably sliced the onions too thin using the mandolin. Mandolins are very abrasive on onions, breaking all the cell walls, so they probably leaked out all the moisture quickly and burned. When I make this recipe, I rough chop them. Hope this helps!